He went to the Cooley Dickinson Hospital emergency room that day and on Friday underwent surgery to repair the tendon and reset the knee cap at Hampshire Orthopedics and Sports Medicine.

For now, he is getting around on crutches. “My orders are to stay off the leg, keep it in the brace and keep it straight,” he said.

The chief said he will know more about his recovery after a follow-up appointment Jan. 16. His treatment will include physical therapy, he said.

He is now able to access his work computer from home, so he can do a few hours of work a day there, including answering emails and “shuffling paperwork,” he said. Since he was injured off the job, the rest of his time out will be sick time.

Starting next week, McMahon said, he hopes to be able to spend some time in the Public Safety Complex, although he won’t be putting in eight-hour days for a while.

What makes it a bit harder to swallow for McMahon is that he was scheduled to take a two-week vacation to Key West, Fla., starting Jan. 3.

“I’m sitting here looking at snow, and I could be in Key West looking at beach sand,” he said. “But it was a freak accident. It happened and I’ve got to live with it and make the most of it.”

McMahon, a 33-year veteran of the Police Department, said he is confident the department will run as smooth as ever without him.

“They can definitely run it very well, there are a lot of good officers on the job,” he said. “And it’s not like I’m completely gone, I’m just a phone call away if anyone has a question.”